Wireless networks have become quite popular, but higher throughput networks are constantly in demand. However, as newer and faster network devices become available, not all prior generations of devices disappear, so coexistence and interoperability of old and new devices must be addressed.
An example wireless network is one that operates according to one or more wireless protocol standards published by the IEEE (“Institute of Electrical and Electronics Engineers”), such as the IEEE 802.11 for Wireless LAN (“local area network”) or WLAN standards that have been widely adopted for use in wireless networking devices. The IEEE 802.11 standard continues evolve as new amendments are ratified. Currently, the IEEE 802.11 standard comprises several modulation techniques that all use the same communication protocol, including the 802.11a, 802.11b, and 802.11g amendments to 802.11.
The 802.11a, 802.11b, and 802.11g standards are used extensively in wireless networking devices. Devices that use the 802.11 a standard operate in a 5 GHz (gigahertz) frequency band, and 802.11b and 802.11g devices operate in a 2.4 GHz frequency band. The 802.11 a standard provides for higher data rates than the 802.11b standard, but the 802.11 a standard provides a significantly shorter range than the range of 802.11b and 802.11g devices. Devices operating according to the 802.11a standard are not normally interoperable with 802.11 b/g devices. However, some devices are adapted to support both 802.11a and 802.11b/g. The 802.11b and 802.11g standards are interoperable, but in some older networks the presence of a 802.11b device may cause significant slowing of 802.11g compliant devices in order to accommodate the 802.11b compliant device.
The 802.11a/b/g WLAN standards may provide adequate performance for many wireless networking applications. However, as next generation high throughput (HT) devices providing higher performance are developed and become available, HT devices will need to coexist with legacy devices supporting older standards. For example, HT devices using IEEE 802.11n will need to be able to coexist and interoperate with legacy devices using the 802.11 a/b/g WLAN standards, since legacy devices using these standards are not likely to disappear from use immediately upon the introduction of next generation devices.
Coexistence is where differing devices can operate in a common space and still perform most or all of their functions. For example, a HT transmitter transmitting to an HT receiver might coexist with a legacy transmitter transmitting to a legacy receiver and the HT devices can communicate while the legacy devices communicate, or at least where the two domains are such that one defers to the other when the other is communicating. Coexistence is important so that the adoption and/or use of HT devices do not require the replacement or disabling of existing infrastructures of legacy devices.
Interoperability is where a HT device and a legacy device can communicate. For example, a HT device might initiate a transmission in such a manner that a legacy device can receive the data sent by the HT transmitter and/or indicate that it is a legacy device so that the HT transmitter can adjust its operations accordingly. For example, the HT transmitter might revert to standards compliant communications or switch to a mode that, while not fully standards compliant, is available to the legacy receiver. In another situation, a HT receiver might successfully receive data from a legacy transmitter.